With the recent increase in concern about environmental issues, the demand on automobiles for better fuel economy has been increasing. Better fuel economy is also required of rubber compositions for automotive tires. For example, rubber compositions containing a conjugated diene polymer such as polybutadiene or butadiene-styrene copolymer and filler such as carbon black or silica are used in automotive tires.
Patent Literature 1, for example, proposes a method for improving fuel economy by using a diene rubber which has been modified with an organosilicon compound containing an amino group and an alkoxy group. These days, however, further improvement of fuel economy has been demanded. Rubber compositions for automotive tires are also required to have properties including wet-grip performance. However, such properties are usually in a trade-off relationship with fuel economy. Thus, it has been difficult to provide a good balance of high levels of each property.